A liquid ejection head, which ejects liquid from a nozzle orifice in the form of a droplet by causing a pressure fluctuation in the liquid stored in a pressure chamber, includes a recording head, a liquid crystal ejection head, and a coloring material ejection head, for example. The recording head is to be provided in an image recording apparatus such as a printer or a plotter and ejects liquid ink in the form of ink droplets. The liquid crystal ejection head is to be used with a display manufacturing system for manufacturing a liquid crystal display. In the display manufacturing system, liquid crystal which has been ejected from a liquid crystal ejection head and assumes the form of a droplet is ejected toward a predetermined grid of a display substrate having a plurality of grids. The coloring material ejection head is to be used with a filter manufacturing system for manufacturing a color filter and ejects a coloring material on the surface of a filter substrate.
Such a liquid ejection head comes in various types. One type of such a liquid ejection heads ejects a droplet by flexural deformation of a piezoelectric vibrator formed on the surface of a vibration plate. The liquid ejection head comprises an actuator unit having, e.g., a pressure chamber and a piezoelectric vibrator; and a channel unit having nozzle orifices and a common liquid chamber. The liquid ejection head varies the volume of the pressure chamber by deforming the piezoelectric vibrator, which is provided on a vibration plate, thereby causing pressure fluctuations in the liquid stored in the pressure chamber. By utilization of the pressure fluctuations, a droplet is ejected from the nozzle orifice. For instance, liquid is compressed by contraction of the pressure chamber, thereby squeezing the liquid out of the nozzle orifice.
In general, the above piezoelectric vibrator has a single-layer structure comprising: a piezoelectric layer; a drive electrode formed on one surface of the piezoelectric layer and electrically connected to a supply source of a drive signal; and a common electrode formed on the other surface of the piezoelectric layer. Since the size of the piezoelectric vibrator is determined in accordance with an area of the pressure chamber, the deformable amount of the piezoelectric vibrator in the liquid ejection head is approximately 0.11 μm at most. Namely, if the voltage applied between the electrodes is increased to increase the deformed amount of the piezoelectric vibrator, the stress is concentrated to the joining face of the piezoelectric vibrator and the vibration plate, so that the piezoelectric layer is peeled off the vibration plate. In order to avoid this problematic situation, the thickness of the piezoelectric vibrator may be increased. However, it is impractical because more time would be necessary for fabricating such a thick piezoelectric vibrator, thereby increasing costs.